Both Palatable and Unpalatable Butterflies Use Bright Colors to Signal Difficulty of Capture to Predators

Abstract

Birds are able to recognize and learn to avoid attacking unpalatable, chemically defended butterflies after unpleasant experiences with them. It has also been suggested that birds learn to avoid prey that are efficient at escaping. This, however, remains poorly documented. Here, we argue that butterflies may utilize a variety of escape tactics against insectivorous birds and review evidence that birds avoid attacking butterflies that are hard to catch. We suggest that signaling difficulty of capture to predators is a widespread phenomenon in butterflies, and this ability may not be limited to palatable butterflies. The possibility that both palatable and unpalatable species signal difficulty of capture has not been fully explored, but helps explain the existence of aposematic coloration and escape mimicry in butterflies lacking defensive chemicals. This possibility may also change the role that putative Müllerian and Batesian mimics play in a variety of classical mimicry rings, thus opening new perspectives in the evolution of mimicry in butterflies.

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Acknowledgments

We are grateful to José R. Trigo for discussions on butterfly chemical defenses and three anonymous reviewers for helpful comments on the manuscript. CEGP thanks FAPDF/CNPq/Pronex (project number 563/2009). AVLF thanks the Brazilian Research Council – CNPq (fellowship 302585/2011-7 and SISBIOTA-Brasil/CNPq 563332/2010-7), the National Science Foundation (DEB-1256742), and FAPESP (BIOTA-FAPESP Program, 2011/50225-3).